Coil Tube Injector System

ABSTRACT

A coil tube injector head comprising at least two gearbox units, wherein each gearbox unit drives a gripper assembly comprising a plurality of gripper assembly links. The gripper assembly links comprise a gripper surface that engages a length of coil tubing and one or more roller bearings that engage a bearing plate. The coil tube injector head further comprises a skid plate that is coupled to the bearing plate and receives pressure from one or more traction cylinders. The assembly of the claimed embodiments further allows for ease of maintenance and service of the coil tube injector by operators in the field of oil and gas production.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/811,219, filed Apr. 12, 2013, which is incorporated herein byreference for all purposes.

BACKGROUND

Hydrocarbons are an important resource which are often retrieved fromground by performing various subterranean operations. When performingsubterranean operations, coil tube injector heads may be used to directcoil tubing (e.g., tubing which may be in a range of from approximately1″ to approximately 3½″) into and out of a wellbore. The injectorsprovide a means of gripping the tubing to perform a controlled feedingoperation. Injector heads are rated against the pushing/pulling forcethey can generate and the feedrate at which the tubing can be passed.

A complete injector head may comprise several components. For instance,the injector head may include an injector head assembly; a crash frame(providing a degree of mechanical protection during service); a serviceplatform (allowing the operators to manage the operation of coil tubeinjection during service); and a gooseneck (which controls the feed ofthe tubing into the injector from a separate coil tube spool).

The basic premise of a coil tube injector is to simply grip the tubingwith sufficient traction so that it does not slip when performing thedesired subterranean operations, and then either pushing the tubing intoa well or extracting it out. To achieve this goal, generally there aretwo sets of grippers, attached to a chain drive mechanism. The drivesare generally hydraulically powered and when combined with a reductiongearbox provide sufficient torque to adequately move the loads. It isdesirable to have an injector head which can operate smoothly and whichcan be easily maintained and serviced without disrupting ongoingsubterranean operations.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete and thorough understanding of the present embodimentsand advantages thereof may be acquired by referring to the followingdescription taken in conjunction with the accompanying drawings.

FIG. 1 is an illustration of a coil tube injector configuration inaccordance with certain embodiments of the present disclosure.

FIG. 2A is a first perspective view of the injector head assembly ofFIG. 1 in accordance with an illustrative embodiment of the presentdisclosure.

FIG. 2B is a second perspective view of the injector head assembly ofFIG. 1 in accordance with an illustrative embodiment of the presentdisclosure.

FIG. 2C is a third perspective view of the injector head assembly ofFIG. 1 in accordance with an illustrative embodiment of the presentdisclosure.

FIG. 3A is a side close up view of the injector head assembly of FIGS.2A-C in accordance with certain embodiments of the present disclosure.

FIG. 3B is a cross-sectional view of the injector head assembly of FIG.3A in accordance with certain embodiments of the present disclosure.

FIG. 3C is a cross-sectional view of the injector head assembly of FIG.3A with one side of the crash frame removed, in accordance with certainembodiments of the present disclosure.

FIG. 4 is a close up view of one of the chain links of a gripper/chainassembly in accordance with certain embodiments of the presentdisclosure.

DETAILED DESCRIPTION

Illustrative embodiments of the present invention are described indetail herein. In the interest of clarity, not all features of an actualimplementation may be described in this specification. It will of coursebe appreciated that in the development of any such actual embodiment,numerous implementation specific decisions must be made to achieve thespecific implementation goals, which will vary from one implementationto another. Moreover, it will be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking for those of ordinary skill in the art having thebenefit of the present disclosure.

To facilitate a better understanding of the present invention, thefollowing examples of certain embodiments are given. In no way shouldthe following examples be read to limit, or define, the scope of theinvention. Embodiments of the present disclosure may be used with anywellhead system. Embodiments of the present disclosure may be applicableto horizontal, vertical, deviated, or otherwise nonlinear wellbores inany type of subterranean formation. Embodiments may be applicable toinjection wells as well as production wells, including hydrocarbonwells.

The terms “couple” or “couples” as used herein are intended to meaneither an indirect or direct connection. Thus, if a first device couplesto a second device, that connection may be through a direct connection,or through an indirect mechanical or electrical connection via otherdevices and connections.

The methods and systems disclosed herein are not limited to anyparticular unit size. For instance, in certain implementations, theinjector head unit may be an ‘80 k’ (80,000 psi) unit. However, thedesign concept can easily be upscaled and downscaled to suit the actualrequirements. The methods and systems disclosed herein are directed toan actual operation constraint with regard to ease of operation andmaintenance, making a ‘simple’ unit which is easily maintained andtherefore, can be kept in production.

A coil tube injector in accordance with an illustrative embodiment ofthe present disclosure is generally denoted with reference numeral 100in FIG. 1. As shown in FIG. 1, a coil tube injector 100 is comprised ofan injector head assembly 102, a crash frame 104 that providesmechanical protection to the injector head assembly 102, a serviceplatform 106 that allows the operators to perform service on the coiltube injector 100 and manage the operation of the coil tube injector 100during service, and a gooseneck 108 that controls the feed of the coiltubing 110 into the injector head assembly 102 from an external coiltube spool (not shown). Specifically, a spool (not shown) may bedisposed near the coil tube injector 100 and a coil tubing 110 may bedrawn from the spool and directed over the gooseneck 108, and throughthe injector head assembly 102, into the wellbore.

FIGS. 2A-C depict different perspectives of a close up view of theinjector head assembly 102 of FIG. 1, in accordance with an illustrativeembodiment of the present disclosure. As shown in FIGS. 2A-C, theinjector head assembly 102 may include a pair of gearbox units 202A,202B, each coupled to a corresponding gripper/chain assembly 204A, 204B,respectively. In certain implementations, the gearbox units 202A, 202Bmay be a hydraulic drive gearbox unit. Accordingly, each gripper/chainassembly 204A, 204B may be driven by the corresponding gearbox unit202A, 202B. The injector head assembly 102 may further include one ormore traction cylinders 206 that operate to apply pressure to skidplates 208.

Turning now to FIG. 3A-C, the operation of the traction cylinders 206and the skid plate 208 in accordance with an illustrative implementationof the present disclosure is disclosed in further detail. Specifically,FIG. 3A depicts a side close-up view of the injector head assembly 102of FIG. 1 and FIGS. 2A-2C. FIG. 3B depicts a cross-sectional view of theinjector head assembly 102 of FIG. 3A. Similarly, FIG. 3C depicts across-sectional view of the injector head assembly of FIG. 3A with oneside of the crash frame 104 removed to show the components as they areconfigured therein.

As shown in FIG. 3A-C, each skid plate 208 is coupled to a bearing plate212. The skid plates 208 and the bearing plates 212 may be made from anysuitable material known to those of ordinary skill in the art. Forinstance, in certain illustrative embodiments, the skid plates 208 maybe made from high grade aluminum and the bearing plates 212 may be madefrom hardened steel. The bearing plates 212 provide the wearing surfacethat is in contact with the roller bearings of the gripper/chainassembly 204, as discussed in more detail below.

FIG. 4 depicts a close-up view of one of a chain link of a gripper/chainassembly 204A, 204B which is denoted generally with reference numeral400. In certain illustrative embodiments, the chain link 400 may consistof a roller bearing 402 on one side and a gripper 404 on the other side.As shown in FIG. 4, the roller bearing 402 may be disposed on the sideopposite to the gripper 404.

Each gripper/chain assembly 204A, 204B may have a plurality of chainlinks 400 each having one or more roller bearings 402 and one or moregrippers 404 as shown in FIG. 4. The grippers 404 are configured toengage a length of coil tubing running through the injector headassembly 102. In certain illustrative embodiments, each gripper 404 maybe configured as a semi-cylinder shaped cut-out allowing the surface ofthe gripper 404 to engage a greater area of the coil tubing 110 and moreevenly apply pressure to the coil tubing 110. The cut-out for a gripper404 may be sized differently to engage with different sizes of coiltubing 110. As shown in FIGS. 3A-C and FIG. 4, the gripper 404 may becoupled to roller bearings 402, which in turn engage a bearing plate212. The use of roller bearings 402 serves to reduce friction betweenthe gripper/chain assembly 204A, 204B and the corresponding bearingplate 212 by allowing the roller bearings 402 to roll across the surfaceof the bearing plate 212. Multiple links in the gripper/chain assembly204 may be coupled through chain links 400. This arrangement permits anoperator to replace/repair either one gripper 404 at a time or toreplace/repair the entire gripper/chain assembly 204A, 204B in oneservice operation. Replacing the entire gripper/chain assembly 204A,204B in one operation ensures that all grippers 404 operate in a similarcondition, i.e., a singular worn item does not get maintained with thesystem. This also allows service to be performed in a shorter amount oftime.

Returning to FIGS. 3A-C, the bearing plates 212 which are coupled tocorresponding skid plates 208 provide a wearing surface for rollers 402on the gripper/chain assembly 204. The traction cylinders 206 providethe force to push and pull the skid plate 208 so as to engage thebearing plate 212 with the gripper/chain assembly 204. Accordingly, thetraction cylinders 206 can move the skid plates 208, and in turn, thebearing plates 212, between different positions to apply more, or lesspressure, on to the coil tubing 110. For instance, the tractioncylinders 206 may move the skid plates 208 and the bearing plates 212between a first position which is further from the coil tubing 110 beingdirected through the injector head assembly 102 and a second positionwhich is closer to the coil tubing 110. Accordingly, this configurationof the bearing plates 212 provides for reduced friction under load andprovides a means of controlling the pressure on each gripper 404 as itis engaged within the load cycle via the skid plate 208 and tractioncylinders 206.

Specifically, FIG. 3B provides an illustration of the injector headassembly 102 focusing on the interaction of the skid plate 208, thebearing plate 212, and each gripper/chain assembly 204A and 204B. Theoperation of the injector head assembly 102 is now discussed inconjunction with one of the gripper/chain assemblies 204A. The othergripper/chain assembly 204B operates in the same manner. As shown inFIG. 3B, traction cylinders 206 apply pressure to the skid plate 208,which in turn applies pressure to the bearing plate 212. This brings thebearing plate 212 into contact with the gripper/chain assembly 204A,enabling the roller bearings 402 of the gripper/chain assembly 204A toroll across the surface of the bearing plate 212. Additionally, thepressure to the bearing plate 212 engages the grippers 404 of thegripper/chain assembly 204A with a length of coil tubing that is beingdirected between the two gripper chain assemblies 204A and 204B.

FIG. 3C is an illustration of an injector head assembly 102 focusing onthe motion of each gripper/chain assembly 204A, 204B and thecorresponding hydraulic drive gearbox unit 202A, 202B. As shown in FIG.3C, each gripper/chain assembly 204A, 204B is coupled to a correspondingdrive motor 205A, 205B which is driven by the gear box unit 202A, 202B.The drive motors 205A, 205B provide a counter rotation arrangement todirect the coil tubing 110 into the well (or to pull the coil tubing 110out). Specifically, the drive motors 205A, 205B are configured to turnin opposite directions such that the two facing sides of the twogripper/chain assemblies 204A, 204B move in the same vertical direction,i.e., move up together or move down together. In this configuration, oneor more grippers 404 from each gripper/chain assembly 204A, 204B is ableto engage with a length of coil tubing 110 running between the twofacing sides of the two gripper/chain assemblies 204A, 204B.

In operation, the traction cylinders 206 are pressured, moving the skidplates 208 towards the centrally located coil tubing 110 as it ispassing through the gripper/chain assemblies 204A, 204B. Once thegripper/chain assemblies 204A, 204B engage with the coil tubing 110, areaction force is applied back through the bearing plates 212 and theskid plates 208, thereby allowing a precise control of the position andload being applied to the coil tubing 110. This arrangement isreplicated about the vertical centerline of the injector head assembly102, allowing the gripper/chain assemblies 204A, 204B to encapsulate thecoil tubing 110 and move the coil tubing 110 up or down as directed bythe drive motors 205A, 205B. Accordingly, the traction cylinders 206apply pressure to the skid plates 208, to bring the bearing plates 212into contact with the gripper/chain assembly 204A, 204B so as to engagea coil tube 110.

In certain implementations, the skid plate 208, which may bemanufactured from high grade aluminum, may be guided via slides whichare disposed on the skid plate 208. In certain implementations, theremay be four slides, one located at each corner of the skid plate 208.Composite bearings may be used to ensure that the skid plate 208 slidessmoothly on the guides. The traction cylinders 206 provide the force topush and pull the skid plate 208. The skid plate 208 is of a robustdesign to minimize the amount of deflection it will experience under theload condition. Minimizing the distortion ensures that the bearing plate212 provides a smooth and level surface on which the roller bearings 402of the gripper/chain assembly 204 can run.

Returning now to FIGS. 2A-2C, the injector head assembly 102 may furtherinclude one or more tensioning cylinders 210. In certainimplementations, the tensioning cylinders 210 may be disposed to apply aforce in a direction that is substantially perpendicular to thedirection of the force applied by the traction cylinders 206. Thetensioning cylinders 210 are configured to apply sufficient force toensure there is no chain ‘slap’ during operation. Specifically, thetensioning cylinders 210 are operable to maintain a desired degree oftension within the chain/gripper assembly 204. In certainimplementations, the amount of force (pressure) applied to the tractioncylinders 206 is proportional to the amount of grip force that will beexerted to the coil tubing 110.

In certain implementations, the traction cylinders 206 and thetensioning cylinders 210 are located or accessible from the outside ofthe injector head assembly 102. For instance, as shown in FIGS. 2A-C,the traction cylinders 206 and the tensioning cylinders 210 may bemounted to an outer side of the crash frame 104. Accordingly, a singlecylinder (either traction cylinder 206 and/or tension cylinder 210) maybe removed and disengaged from the skid plate 208 to allow forreplacement and/or repair of the cylinder. The remaining cylinders willcontinue to operate. As a result, the operable items may berepaired/replaced insitu and the injector head assembly 102 can remainin position above the well while it is being serviced. Additionally, ina preferred embodiment, the cylinders may all be of the samespecification, simplifying the replacement of any cylinder duringmaintenance.

Accordingly, the use of the roller bearings 402 which run against thebearing plate 212 under the load condition reduces the friction whenoperating under a load. Additionally, the interaction of the bearingplates 212 with the roller bearings 402 of the gripper/chain assembly204 provides a means of controlling the pressure applied by eachgripper/chain assembly 204A, 204B as it engages the coil tubing 110.Specifically, the applied pressure by each gripper/chain assembly 204 ina load cycle may be controlled by an operator using the tractioncylinders 206 which apply pressure to the roller bearings 402 throughthe skid plates 208 and the bearing plates 212.

Moreover, the bearing plates 212 are sacrificial items given the arduousnature of coil tubing. The bearing plates 212 may be accessed from thefront and rear of the injector head assembly 102 and they may be easilyremoved to the sides of the injector head assembly. Accordingly, thebearing plates 212 may be easily replaced and/or repaired in situ.

Additionally, the gripper/chain assemblies 204A, 204B (including thegrippers 404 and the roller bearings 402) are highly loaded duringservice. Accordingly, in certain implementations, the vertical space maybe maximized to allow additional gripper assemblies to be in the loadpath, thus reducing the load to individual grippers 404, which in turnextends the life of the injector head assembly 102. Further, thegrippers 404 are an integral part of the gripper/chain assembly 204.Accordingly, in certain implementations, a gripper carrier allowsindividual replacement of grippers 404. In another embodiment, the wholegripper/chain assembly 204 may be replaced in one operation. Thisresults in a quick service period to change gripper size (e.g., goingfrom 1½″ to 2″) and ensures that all grippers operate in a similarcondition, i.e., a singular worn item does not get maintained with thesystem. When the gripper/chain assembly 204 or the grippers 404 dobecome worn out, an effective replacement can be made in a short timeperiod which may be in a matter of minutes. Operational time istypically of great importance when performing subterranean operations.Accordingly, the longer the machine can operate and maintain performancethe better.

In certain embodiments, different components may be manufactured fromhigh grade aluminum which is sufficiently strong while giving a reducedweight compared to steel (steel being roughly 2½ times the weight ofaluminum). The benefit of reduced weight is the ease of handling duringinstallation, making the operator's job easier and therefore moreproductive.

Therefore, the present disclosure is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified, and all such variations are considered within the scope andspirit of the present invention. Also, the terms in the claims havetheir plain, ordinary meaning unless otherwise explicitly and clearlydefined by the patentee.

What is claimed is:
 1. An injector head assembly comprising: a firstgripper assembly and a second gripper assembly, wherein each of thefirst and second gripper assemblies comprises one or more grippers andone or more roller bearings; a first gearbox unit and a second gearboxunit, wherein the first gearbox unit drives the first gripper assemblyand wherein the second gearbox unit drives the second gearbox assembly;a traction cylinder; a skid plate coupled to the traction cylinder,wherein the traction cylinder applies pressure to the skid plate; abearing plate coupled to the skid plate, wherein the bearing plate is incontact with the one or more roller bearings.
 2. The injector headassembly of claim 1, wherein the pressure applied by the tractioncylinder moves the skid plate and the bearing plate between a firstposition and a second position.
 3. The injector head assembly of claim1, wherein the skid plate is made from high grade aluminum.
 4. Theinjector head assembly of claim 1, wherein the bearing plate is madefrom steel.
 5. The injector head assembly of claim 1, further comprisinga tensioning cylinder, wherein the tensioning cylinder is operable toapply a force in a direction that is substantially perpendicular todirection of a force applied by the traction cylinder.
 6. The injectorhead assembly of claim 1, wherein the skid plate is guided via aplurality of slides, wherein the slides are disposed on the skid plate.7. The injector head assembly of claim 1, wherein the skid plate iscoupled to a plurality of traction cylinders.
 8. The injector headassembly of claim 1, wherein the first gearbox unit drives the firstgripper assembly in a first direction and wherein the second gearboxunit drives the second gearbox assembly in a second direction.
 9. Theinjector head assembly of claim 8, wherein a side of the first gripperassembly faces a side of the second gripper assembly and wherein thefacing sides of the first gripper assembly and the second gripperassembly move in same vertical direction.
 10. A injector head assemblycomprising: a coil tube injector head, wherein the coil tube injectorhead comprises: a first gripper assembly and a second gripper assembly,wherein each of the first and second gripper assemblies comprise one ormore grippers and one or more roller bearings; a first gearbox unit anda second gearbox unit, wherein the first gearbox unit drives the firstgripper assembly and wherein the second gearbox unit drives the secondgearbox assembly; a traction cylinder; a skid plate, wherein thetraction cylinder provides pressure to the skid plate; a bearing plate,wherein the skid plate is coupled to the bearing plate and wherein thebearing plate is coupled to the one or more roller bearings; and whereinthe coil tube injector head controls the feedrate of a length of coiltubing into or out of a well hole.
 11. The injector head assembly ofclaim 10, wherein the pressure applied by the traction cylinder movesthe skid plate and the bearing plate between a first position and asecond position.
 12. The injector head assembly of claim 10, wherein theskid plate is made from high grade aluminum.
 13. The injector headassembly of claim 10, wherein the bearing plate is made from steel. 14.The injector head assembly of claim 10, further comprising a tensioningcylinder, wherein the tensioning cylinder is operable to apply a forcein a direction that is substantially perpendicular to direction of aforce applied by the traction cylinder.
 15. The injector head assemblyof claim 10, wherein the skid plate is guided via a plurality of slides,wherein the slides are disposed on the skid plate.
 16. The injector headassembly of claim 10, wherein the skid plate is coupled to a pluralityof traction cylinders.
 17. The injector head assembly of claim 10,wherein the first gearbox unit drives the first gripper assembly in afirst direction and wherein the second gearbox unit drives the secondgearbox assembly in a second direction.
 18. The injector head assemblyof claim 17, wherein a side of the first gripper assembly faces a sideof the second gripper assembly and wherein the facing sides of the firstgripper assembly and the second gripper assembly move in same verticaldirection.